The present invention is directed to adjustable formwork for forming corner surfaces in concrete structural members. The adjustable formwork includes a pair of formwork units which abut in a corner of the members being formed. The formwork units include formwork supports which extend generally parallel to the concrete surfaces being formed. The formwork supports are connected to one another so that they can be pivotally adjusted and fixed relative to one another.
Formwork for concrete structural members, particularly for members produced in place, such as bridges, include relatively thin planar formwork surfaces which directly form the surface of the structural member. Since the formwork surface, generally a plate-like member, has no great support capacity, it is reinforced or supported by formwork supports. In combination, the formwork surface elements and the formwork supports combine to form formwork units whose position relative to one another can be changed to provide the desired shape of a structural member or to strip the formwork after the concrete has set.
When erecting formwork for so-called inside corners where the concrete surfaces to be poured intersect at an angle less than 180.degree., there is difficulty in stripping the individual formwork units, from the concrete after it has set, by means of pivotal movements. Pivotal or articulated connections for this purpose are always located in the region of the formwork supports transmitting the force, that is, at a distance from the formwork surface or skin with the result that pivotal movements about such articulation point causes the formwork units to become jammed or siezed in the corner against the concrete which has set. In such formwork there must be some provision for releasing the formwork from a corner which often considerably complicates the construction of the formwork.
Particular difficulties arise, for example, when in the formwork for the underside of a bridge superstructure where the roadway slab is carried by longitudinally extending girders, different angular positions must be maintained along the length of the bridge between the outer surfaces of the girder webs and the lower surface of a roadway slab or of an outwardly projecting cantilever section which forms the roadway slab.